A critical look at N-nitrosamines in environmental tobacco smoke.

The amounts of cigarette smoke carcinogens released into the environment as sidestream smoke (SS) constituents are generally twice as high as the levels of the carcinogens that are inhaled as mainstream smoke (MS). However, certain carcinogens in undiluted SS, such as nitrosamines, exceed MS levels up to 50 times. Regardless of the fact that SS is usually substantially diluted before being inhaled, its constituents can be determined in environmental tobacco smoke (ETS) by modern analytical methods and levels of exposure of involuntary smokers can be assessed by the use of specific markers. Currently, the uptake of ETS by nonsmokers is determined by measuring nicotine and its metabolite cotinine in saliva, serum and/or urine. In on-going studies, we are now exploring the determination of the two highly carcinogenic nicotine-derived nitrosamines N'-nitrosonornicotine (NNN) and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), respectively of their metabolites, in physiological fluids of smokers and nonsmokers.